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Matthew Palmer: Invalid Excuses for Why Your Release Process Sucks

Planet Debian - Fri, 2024-11-22 15:15

In my companion article, I made the bold claim that your release process should consist of no more than two steps:

Create an annotated Git tag;
Run a single command to trigger the release pipeline.

As I have been on the Internet for more than five minutes, I’m aware that a great many people will have a great many objections to this simple and straightforward idea. In the interests of saving them a lot of wear and tear on their keyboards, I present this list of common reasons why these objections are invalid.

If you have an objection I don’t cover here, the comment box is down the bottom of the article. If you think you’ve got a real stumper, I’m available for consulting engagements, and if you turn out to have a release process which cannot feasibly be reduced to the above two steps for legitimate technical reasons, I’ll waive my fees.

“But I automatically generate my release notes from commit messages!”

This one is really easy to solve: have the release note generation tool feed directly into the annotation. Boom! Headshot.

“But all these files need to be edited to make a release!”

No, they absolutely don’t. But I can see why you might think you do, given how inflexible some packaging environments can seem, and since “that’s how we’ve always done it”.

Language Packages

Most languages require you to encode the version of the library or binary in a file that you want to revision control. This is teh suck, but I’m yet to encounter a situation that can’t be worked around some way or another.

In Ruby, for instance, gemspec files are actually executable Ruby code, so I call code (that’s part of git-version-bump, as an aside) to calculate the version number from the git tags. The Rust build tool, Cargo, uses a TOML file, which isn’t as easy, but a small amount of release automation is used to take care of that.

Distribution Packages

If you’re building Linux distribution packages, you can easily apply similar automation faffery. For example, Debian packages take their metadata from the debian/changelog file in the build directory. Don’t keep that file in revision control, though: build it at release time. Everything you need to construct a Debian (or RPM) changelog is in the tag – version numbers, dates, times, authors, release notes. Use it for much good.

The Dreaded Changelog

Finally, there’s the CHANGELOG file. If it’s maintained during the development process, it typically has an archive of all the release notes, under version numbers, with an “Unreleased” heading at the top. It’s one more place to remember to have to edit when making that “preparing release X.Y.Z” commit, and it is a gift to the Demon of Spurious Merge Conflicts if you follow the policy of “every commit must add a changelog entry”.

My solution: just burn it to the ground. Add a line to the top with a link to wherever the contents of annotated tags get published (such as GitHub Releases, if that’s your bag) and never open it ever again.

“But I need to know other things about my release, too!”

For some reason, you might think you need some other metadata about your releases. You’re probably wrong – it’s amazing how much information you can obtain or derive from the humble tag – so think creatively about your situation before you start making unnecessary complexity for yourself.

But, on the off chance you’re in a situation that legitimately needs some extra release-related information, here’s the secret: structured annotation. The annotation on a tag can be literally any sequence of octets you like. How that data is interpreted is up to you.

So, require that annotations on release tags use some sort of structured data format (say YAML or TOML – or even XML if you hate your release manager), and mandate that it contain whatever information you need. You can make sure that the annotation has a valid structure and contains all the information you need with an update hook, which can reject the tag push if it doesn’t meet the requirements, and you’re sorted.

“But I have multiple packages in my repo, with different release cadences and versions!”

This one is common enough that I just refer to it as “the monorepo drama”. Personally, I’m not a huge fan of monorepos, but you do you, boo. Annotated tags can still handle it just fine.

The trick is to include the package name being released in the tag name. So rather than a release tag being named vX.Y.Z, you use foo/vX.Y.Z, bar/vX.Y.Z, and baz/vX.Y.Z. The release automation for each package just triggers on tags that match the pattern for that particular package, and limits itself to those tags when figuring out what the version number is.

“But we don’t semver our releases!”

Oh, that’s easy. The tag pattern that marks a release doesn’t have to be vX.Y.Z. It can be anything you want.

Relatedly, there is a (rare, but existent) need for packages that don’t really have a conception of “releases” in the traditional sense. The example I’ve hit most often is automatically generated “bindings” packages, such as protobuf definitions. The source of truth for these is a bunch of .proto files, but to be useful, they need to be packaged into code for the various language(s) you’re using. But those packages need versions, and while someone could manually make releases, the best option is to build new per-language packages automatically every time any of those definitions change.

The versions of those packages, then, can be datestamps (I like something like YYYY.MM.DD.N, where N starts at 0 each day and increments if there are multiple releases in a single day).

This process allows all the code that needs the definitions to declare the minimum version of the definitions that it relies on, and everything is kept in sync and tracked almost like magic.

Th-th-th-th-that’s all, folks!

I hope you’ve enjoyed this bit of mild debunking. Show your gratitude by buying me a refreshing beverage, or purchase my professional expertise and I’ll answer all of your questions and write all your CI jobs.

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